Underground Water Mains Leak Detection in Great Coates

Symptoms

The cold mains pipe runs from the garage through an external wall and into the rear garden, supplying an outside tap and a separate outbuilding. With no external meter at the property, there was no automatic indication of how long the loss had been occurring or how much water had been wasted.

A water mains leak detection investigation was needed to confirm the source and allow a targeted repair.

Methods Used

With the leak confirmed on the cold mains, air was charged to 1 bar and acoustic listening was used to walk the likely pipe route through the rear garden. A leak sound was clearly audible at the point where the cold mains exits through the external wall.

This is a standard approach in water mains leak detection — using pressure to make the escaping air audible, then tracing it to the exact source. Floor slates were lifted at that location to expose the pipe.

Investigation Process

1. 1
   Visual inspection completed

   The property and toilets were visually inspected. Nothing was found wet inside the property.

2. 2
   Stopcock test confirmed mains source

   Audible water running in the mains pipework was noted. Turning off the internal stopcock in the garage stopped the noise, confirming the loss was on the mains supply.

3. 3
   Pressure test — initial

   The pressure test rig was connected downstream of the stopcock in the garage and charged to 2 bar. Pressure dropped instantly on isolation, confirming an active leak.

4. 4
   Boiler feeds isolated, test repeated

   Hot and cold feeds to the combi boiler were isolated and the pressure test was repeated with the same result, ruling out the heating system and confirming the fault on the cold mains.

5. 5
   Acoustic survey of rear garden

   The system was charged to 1 bar and acoustic listening was used to walk the pipe route into the rear garden. A clear leak sound was detected at the point where the cold mains passes through the external wall.

6. 6
   Floor slates lifted, leak exposed

   The floor slates at the external wall were removed, exposing a 15mm copper pipe with a split along its length.

7. 7
   Pipe section replaced and insulated

   The split section of copper pipe through the wall was replaced and connected on both sides. An isolation valve was added in the garage and the new pipe was insulated.

Result & Outcome

Some sand will need to be laid on the exposed external ground and the floor tiles relaid to finish the reinstatement. No further investigative work is required — the source has been confirmed and the repair completed.